Bulk containers made of various materials and in a variety of shapes are used for shipping, storing and displaying many products, including fresh produce such as watermelon. Bulk containers made of corrugated paperboard, in particular, are popular because of their relatively low cost, light weight and recyclability. Among these, bulk containers having an octagonal cross-section are in widespread use because of their strength and other desirable attributes. For example, an octagonal container has greater stacking strength and experiences less outward bulge of the sidewalls than a comparably sized rectangular or square container. On the other hand, square or rectangular containers better fit on and fill out the available space on the square or rectangular pallets commonly used with these containers. Square or rectangular containers also offer greater graphics capabilities than octagonal containers.
Further, to reduce the cost of storage and shipment, many prior art containers are shipped to the point of use in a knocked-down or flattened condition, and then erected or set up into a ready-to-use condition at the point of use. Conventional constructions can be difficult to manipulate from a flattened condition to a set-up condition, resulting in increased labor costs and dissatisfaction.
Examples of prior art octagonal containers are described in commonly owned U.S. Pat. Nos. 5,139,196 and 6,386,437. These containers have an octagonal shape at both their inner and outer surfaces, and are shipped to the user in a flattened condition. They both incorporate a bottom locking structure intended to facilitate moving the containers from a flattened condition to a set-up condition.
Examples of prior art containers having a square or rectangular outer shape are described in U.S. Pat. Nos. 2,295,141, 4,151,948, 5,294,044 and 6,481,619. All of these except the '619 patent also have interior diagonal corner panels to increase the stacking strength of the container.
The diagonal corner panels in the '141 patent are formed by extension flaps 7 on the side edges of end roll-over panels 6. The roll-over panels also capture end flaps 4 on adjacent sidewall panels, and have locking tabs 9 on their bottom edges, which engage in openings 10 at the juncture of the end walls with the bottom wall to hold the roll-over panels and the sidewalls in place. Extensions 8 on the outer edges of the flaps 7 are reversely folded to lie along an inner surface of the adjacent sidewall and abut against the adjacent end wall.
The diagonal corner panels 32 in the '948 patent also are formed on opposite side edges of end roll-over panels 30, which have a locking tab 22 on their bottom edges that engage in openings 23 to hold the roll-over panels in place. The roll-over panels also capture double-folded flaps 24 and 26 on the ends of sidewall panels to hold them in place.
In the '044 patent, gusset or pleat folds 64 at the junctures of adjacent side and end wall panels are folded together and glued to form a vertical reinforcement in the corners. The diagonal corner panels are formed by extension flaps 68 on opposite sides of opposed end roll-over panels 48 and 50. Glue flaps 70 on the outer edges of the flaps 68 are glued to the adjacent side walls 24 and 28 to hold the diagonal corner panels in place.
None of the foregoing patents discloses or suggests a bulk container that is shipped in a flattened condition and is set up at the point of use to form a container having a square or rectangular outer configuration and an octagonal inner configuration, wherein all four side walls, i.e., the side walls and the end walls, comprise inner and outer wall panels to form a double thickness wall. Further, none of the foregoing patents discloses such a double-walled container wherein the container is held in set-up condition solely by interlocking engagement of the parts, and further wherein the container has a quick-lock bottom structure.
Accordingly, there is need for an easy to erect bulk container that has the strength of an octagonal container and the pallet-fitting shape and graphics capability of a square or rectangular container.